Johns Hopkins University Applied Physics Laboratory's Stamatios (Tom) Krimigis, principal investigator for Voyager's Low-Energy Charged Particle (LECP) instrument, said Voyager is now leaving the solar bubble at an altitude of 11.3 billion miles.
Voyager 1 first detected the pressure of interstellar space on the heliosphere, the bubble of charged particles surrounding the Sun that reaches far beyond the outer planets, in 2004.
Scientists then ramped up their search for evidence of the spacecraft's interstellar arrival, knowing the data analysis and interpretation could take months or years. Until mid-2010, the intensity of particles originating from inside our solar system had been holding steady.
A coronal mass ejection - or a massive burst of solar wind and magnetic fields - that erupted from the Sun in March 2012 provided scientists with the data they needed.
When the material eventually arrived at Voyager 1's location 13 months later, in April 2013, the plasma around the spacecraft began to vibrate like a violin string. On April 9, Voyager 1's plasma wave instrument detected the movement.
The particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere. Density of this sort is to be expected in interstellar space.
The plasma wave science team went back through its recent data and found an earlier, fainter set of oscillations in October to November of 2012.
The report on this has been published in the journal Science.
--ANI (Posted on 13-09-2013)